Apparatus for thermal treatment of free-flowing materials and slurry

ABSTRACT

AN APPARATUS FOR THERMALLY TREATING FREE-FLOWING SLURRY COMPRISES A ROTABLY SUPPORTED HEATED DRUM. CHARGING AND A DISCHARGING DVICES ARE POSITIONED RESPECTIVELY AT THE OPPOSITE ENDS OF THE DRUM. A RECIRCULATION TUBE IS MOUNTED IN THE DRUM AND INCLUDES INTERNAL FINS. A MIXING DEVICE IS PROVIDED AT THE OUTLET OF THE CHARGING DEVICE AND RECIRCULATION TUBE. A DISTRIBUTING DEVICE IS ARRANGED AT THE INLET OF THE   DISCHARGING DEVICE AND INCLUDES A PLURALITY OF SCOOPS FIXED TO THE DRUM, AND WHICH SCOOPS INCLUDE DISHCARGE TROUGHS DIRECTED INTO THE RECIRCULATION TUBE AND INTO THE DISCHARGING DEVICE.

United States Patent [72] Inventor Nlson Moshltovich Boguslavsky 3,240,367 3/1966 Backstrom 263/33 Sadovaya-Chernogryazskaya, ll/2,kv. 37, 3,443,909 5/1969 Goossens 263/34(X) A 1 No g z zz Primary Examiner-John .l.Camby t fg 20 1969 Attorney-Waters, Roditi, Schwartz & Nissen 9 [45] Patented June 28, 1971 [54] APPARATUS FOR THERMAL TREATMENT OF FREEJLOWING MATERIALS AND SLURRY ABSTRACT An apparatus for thermally treating free-flowrng 2 Claims, 3 Drawing 18$ slurry comprises a rotatably supported heated drurn. Charging and a discharging devices are positioned respectively at the [52] US. Cl 263/32 opposire ends of the drum. A recirculation tube is moumed in [51] Int-Cl F27! 7/04 the drum and includes internal fins. A mixing device is pro [50] Field of Search 263/32, 33, vided at h Dune of the. charging device and recirculation 34 tube. A distributing device is arranged at the inlet of the discharging device and includes a plurality of scoops fixed to [56] References Cited the drum, and which scoops include discharge troughs UNITED STATES PATENTS directed into the recirculation tube and into the discharging 1,459,923 6/1923 Nagel 263/33 device.

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SHEET 2 0F 2 FIG. 5

FIGZ

APPARATUS FOR THERMAL TREATMENT OF FREE- FLOWING MATERIALS AND SLURRY The present invention relates to an apparatus for thermal treatment (e.g., drying, destructive distillation or roasting) of free-flowing materials and slurry, particularly of stock tending to stick and lump, in which the heat flows through the heating surfaces and in which the source material, of single or multicomponent character, is prepared and mixed, prior to being fed to the heating surfaces, with dried or roasted product for the purpose of improving the flow of stock to the heating surfaces and preventing the source material from lumping and sticking to the apparatus walls.

Known in the art is an apparatus for thermal treatment of free-flowing materials and slurries, particularly of stock tending to stick and lump (see USSR Inventor's Certificate, No. 101437, 1955), which is essentially a horizontal rotary drum with a drive and means of heating. A recirculation tube, axially arranged inside the drum, serves to return some of the dry product to a feeding device at the end of the drum for mixing it with wet source material. Positioned at the opposite end of the drum is a discharging device comprising a screw arranged axially at the end face. The dried product is distributed for discharging and recirculation in the following way. Blades, provided inside the drum at its discharge end, pick up the stock and deliver it into the screw. The surplus material not capable of passing through the intake of the screw, falls inside the recirculation tube and is delivered to the feeding side of the drum for mixing with wet material.

A disadvantage of the known apparatus is its inability to ensure a stable proportion between the wet material and the dried product in the mixture fed to the heating surfaces of the drum owing to the fact that the capacity of the screw is not only a function of its speed but also depends on the space factor, which is anything but constant.

An object of the present invention is to eliminate the aforesaid disadvantages.

A particular object of the present invention is to provide an apparatus for thermal treatment of free-flowing material and slurry in which the flow of dried product is distributed and fed for discharging and recirculation in a fixed proportion.

This object is accomplished with the aid of an apparatus for thermal treatment of free-flowing materials and slurry, particularly of stock tending to stick and lump, which comprises a horizontally arranged rotary drum with a drive and means of heating; a charging device and a discharging device placed at the opposite ends of the drum; a recirculation tube mounted axially in the drum and fitted with internal helically shaped fins; a mixing device located at the outlets from the charging device and recirculation tube; and a distributing device which is arranged at the inlets to the discharging device and recirculation tube, wherein, according to the present invention, the distributing device is fashioned as a plurality of scoops disposed along the entire periphery of, and rigidly fixed to, the drum, said scoops being provided with discharge troughs so arranged that some of them are directed into the recirculation tube and the other, into the discharging device.

It is preferred to interconnect the adjacent scoops with oppositely directed discharge troughs by means of controllable interflow arrangements.

The invention will be best understood from the following description of a preferred embodiment of the present invention when read in connection with the drawings, illustrating:

FIG. 1 which is a longitudinal sectional view of an apparatus for thermal treatment of free-flowing materials and slurry, according to the present invention;

FIG. 2 which is a section through II-II of FIG. I; and

FIG. 3 which is a section through III-III of FIG. 1 (heating tube banks shown partially).

Referring to FIG. 1, the apparatus is a drum 1 with rims 2 for mounting it on support rollers 3 (FIG. 2) and with a ring gear 4 (FIG. 1) for obtaining rotary motion from a drive (not shown). A spring-type sealin g arrangement 5 serves to provide a connection between the drum 1 of the apparatus and a stationary charging chamber 6 through which the vapors and gases discharged from the free-flowing material can escape into the dust-extracting equipment (not shown).

Fitted to the chamber 6 is a charging device made as a sectional feeder 7 (or a feeder or any other type) for feeding the wet material. The dust separated from the exhaust gases and vapors in the dust-extracting equipment is returned to the chamber 6.

Arranged in the lower part of the chamber 6 is a mixer 8 which prepares a free-flowing stock from wet material and dried or roasted product. The mixer 8 can have one or more shafts with blades of any shape or can be designed on any other lines to suit any particular application.

The chamber 6 is provided with a union 9 through which the gases and vapors escape into the dust-extracting equipment, manholes 10 for inspecting and repairing the apparatus, and windows 11 (FIG. 2) arranged on either side of the mixer for cleaning the latter.

Mounted axially in the drum I (FIG. I) by means of two supports 13 is a recirculation tube 12; one of the supports 13 being of the sliding type to compensate for possible elongation of the tube 12 and its displacement with respect to the drum 1 when hot.

The supports 13 of the tube 12 are heavy rings 14 braced by braces 15 which provide for a rigid connection between the tube 12 and the drum I of the apparatus and enable the tube 12 to rotate integrally with the drum 1. I

Welded to the inside of the tube 12 are helical fins 16 which impart motion to the dried or roasted product in the tube 12, as this is set rotating, and feeds it towards the mixer 8 for mixing it with the wet material fed by the feeder 7.

The discharge end of the drum 1 is rigidly coupled to a discharge chamber 17 which accommodates a distributing device constituted of circumferentially fitted scoops 18 with discharge troughs 19.

The discharge troughs 19 are arranged in a gap between a discharge tube 20 serving to discharge the finished product and the tube 12 in such a way that some of the troughs are directed into the tube 12 (as the trough with a side 21 by way of illustration) and the other, into the discharge tube 20 (the trough with a side 22 provides another example). The adjacent scoops I8 and 18" (FIG. 3) with oppositely directed discharge troughs 19 and are interconnected through a controllable interflow arrangement in the form of a rotatable gate 23 which provides a means of fixing a certain proportion between the amount of the material diverted into the recirculation tube 12 (FIG. 1) and that discharged from the apparatus for further use. The total number of the scoops l8 and also the ratio between the number of the scoops l8 communicating with the tube 12 by way of their discharge troughs 19 and that of the scoops l8 communicating with the discharge tube 20 by way of their discharge troughs 19 depend on the ratio which it is desirable to obtain in the mixer 8 between the dried material fed from the tube 12 and the wet material coming from the feeder 7.

The construction of the discharge tube 20 is in principle not unlike that of the recirculation tube 12 except fins 24 (FIG. 1) of the discharge tube 20 which are arranged in the opposite direction as compared with the fins 16 of the tube 12. The discharge tube 20 connects to a stationary reception chamber 25 for the dried product by means of a spring-loaded sealing arrangement 26. The reception chamber 25 communicates with the storage area by way of conveying pipes 28 and a sectional rotary gate 27 arranged at the bottom of the reception chamber.

The drum 1 can be heated by any arrangement depending on the heat carrier used. The apparatus shown in the drawings can be heated by steam, hot water, or an organic heat carrier, such as a vaporous or a liquid carrier.

The drum 1 is fitted with several concentric rows of heating tubes 29, finned or plain depending on the requisite area of heat transfer and the temperature of the heat carrier and the treated material. The tubes 29 are grouped into banks and secured to tube sheets 30 at the discharge end of the drum I by flaring or welding.

The tube sheet 30 of each tube bank is connected to a cover plate 31 which provides an inlet for the steam and outlet for the condensate or an inlet and outlet for the heat carrier.

A head 32 for admitting steam into, and removing condensate from, the apparatus, or for admitting and removing a liquid heat carrier, is arranged axially in the drum 1 and is exactly of the same design as the heads used with the conventional rotary-type steam-heated calcinators. H6. 1 shows tubes 33 and 34 for admitting the heat carrier and removing the condensate, respectively. The fact that the tubes 29 are grouped into self-contained banks facilitates repair of the apparatus and reduces the weight of the cover plates 31. With this arrangement it is also possible to disconnect any bank of the tubes 29 without stopping the apparatus for an overhaul.

The apparatus provided by the invention can also be operated when heated externally by flue gases. In this case, the tubes 29, cover plates 31, and head 32 are absent and the ring gear 4 is arranged outside the support rollers 3. The length of the drum 1 between the support rollers 3 is enclosed into a brick fire chamber with the flues so arranged that both a for ward and reverse flow of the flue gases can be obtained for heating the material. To enlarge the heating surface (and, consequently, to increase the capacity of the apparatus) the drum I can be finned externally and also internally along the second half of its length in the direction of flue gases flow. The fire chamber burns fuel of any kind.

The apparatus operates as described below.

Wet material is fed uniformly and continuously by the feeder 7 into the mixer 8. ln the mixer 8, the wet material is mixed with the dried material fed from the tube 12. The freeflowing stock from the mixer 8 falls on the heating surfaces, i.e., heating tubes 29, and moves then towards the chamber 18 where the scoops 18 pick it up and deliver the stock in a fixed proportion via the troughs 21 and 22 into the tube 12 and the tube 20. From the tube 12, the stock is returned to the mixer 8 and from the tube 20, discharged by way of the sectional rotary gate 27 and the conveying tubes 28.

Thus, the present apparatus provides for a fixed proportion between the dried and wet material in the stock fed to the heating surfaces of the drum 1. This guarantees free flowing of the mixture and prevents the material from lumping and building up inside the drum 1.

Another feature of the apparatus is the possibility of cutting out any bank of the heating tubes without stopping the apparatus for an overhaul.

The problem of maintenance and repair is eased because the main components, such as the charging and discharging chambers, need not to be taken down and also because the size of the cover plates for admitting and removing the heat carrier is a comparatively small one. The fact that the gases and vapors discharged from the material leave by way of the union 9, bypassing the mixer 8, appreciably reduces the dust content in the gases.

1 claim:

1. An apparatus for thermal treatment of free-flowing materials and slurry, particularly of stock tending to stick and lump, said apparatus comprising: a horizontally arranged rotary drum; a drive for said drum; means for heating said drum; a charging device and a discharging device disposed respectively at the opposite ends of said drum; a recirculation tube mounted axially of said drum and including internal helically shaped fins, a mixing device located at the outlets from said charging device and recirculation tube; a distributing device arranged at the inlets to said discharging device and recirculation tube and which includes a plurality of scoops located along the entire periphery of, and rigidly fixed to, said drum, said scoops including discharge troughs so arranged that at least one is directed into said recirculation tube and another, into said discharging device.

2. An apparatus, as claimed in claim 1, in which the adjacent scoops with oppositely directed discharge troughs are interconnected by means of controllable interflow arrangements. 

